1. Field of the Invention
The present invention relates to a cooling device of Stirling circulated dry storage container, and it specifically means a cooling device that does not need the additional supply of power, has economic efficiency, and can operate stably for a long time.
2. Description of the Prior Art
For the processing of high radiation level waste such as used nuclear fuel, currently in the world's nuclear electricity industry for the initial stage (within five years), spent fuel pool is adopted to accommodate the high radiation level waste; however, after five years, it enters the medium processing stage, and the medium processing stage can be divided into wet storage and dry storage methods. In the wet storage method, high level radiation waste is continuously placed in the cooling system of spent fuel pool so as to use the same method to cool continuously the high level radiation waste, however, in dry cask storage, since the decay heat of the high radiation level waste has been reduced to a level that air convection cooling can be used as a cooling way, and the used fuel is then stored in the cask for cooling.
However, after Mar. 11, 2011, for the Fukushima nuclear plant of Japan, strong earthquake has caused the loss of cooling circulation power in the cooling water of the used fuel pool, and the fuel rods thus got melted and H2 generation is triggered due to the dissolution of Zirconium alloy, hence, people start doubting about the wet storage method which uses the fuel pool for the cooling; hence, after long term cooling of the used fuel rods in the fuel pool, the fuel rods are moved out, and dry storage method is adopted next for the rest of the storage, and this has become the major promotional policy of the nuclear industry in countries around the world.
However, in the above dry storage method, if a low power consumption and stable driving mechanism can be associated to generate sufficient air convection, then a better heat dissipation and temperature reducing effect can be reached, however, among lots of design structures, Stirling heat engine is no doubt a structure that absolutely meets the needed characteristic; currently, for the application of Stirling temperature difference circulation engine to a specific heat source environment, it contains the following different embodiments:
Currently in the US patents, there is no patent regarding the use of Stirling circulation to reach the goal of heat dissipation of used nuclear fuel dry storage system, however, there is a U.S. Pat. No. 5,753,925, which disclosed the design of Radioactive waste storage facility, in that patent, facility type management is adopted to store all the dry containers in the plant, then cold air is used for heat dissipation. However, it is an active heat dissipation system, which needs a driving device.
In addition, in disclosed patent of Republic of China of number 200829144 (application no. of 095149054), an invention patent of “Electronic device and its heat dissipation module” is disclosed, which discloses the structures of heat dissipation module that mainly comprises of: heat conductive substrate, heat dissipation fin, electric fan and Stirling engine; moreover, the heat conductive substrate is installed on the heat source, and heat dissipation fin is connected to heat conductive substrate, meanwhile, the air outlet direction of the electric fan heads towards the heat dissipation fin. Stirling engine has a power input end and a power output end, and power input end is installed on heat conductive substrate, power output end is connected to electric fan so as to use the thermal energy generated by the heat source to drive the Stirling engine, then the Stirling engine will drive the electric fan to do heat dissipation on the heat source. However, during the real application of this structure, since the peripheral is an open space, the electric fan that is driven by Stirling engine will not have good air circulation path during its operation, turbulent effect could easily be generated to affect the entire heat dissipation efficiency.
Therefore, to solve the above drawbacks of the heat dissipation device of the prior art as driven by Stirling engine, the inventor thus provides a way of improvement that leads to the generation of the present invention.